As a anecdote, I have some very interesting and impossible to miss scarring on my arms. I don't hide it, and it is definitely something I know people are curious about. Yet pretty much no one I have interacted with in the last 7 years since moving to a new city knows why, because no one asks.
People I sit with and talk to from 9 to 5 every day, not a word. You notice people glance, you notice some cashiers hesitate, yet just three or four people from memory have asked and it is always an abrupt and outright "so what's up with that?"
I am thankful because it really doesn't affect my life or personal image and so that mentality reflected by others behavior lets me feel justified in that outlook. But there are definitely days where I wonder if people don't ask out of courtesy or because they just don't care either way, and if I am feeling a bit lonley that can be a negative thing rather than a positive.
Mostly though, I just appreciate that people treat me the same as if I didn't have them, whether they have asked what happened or not.